It has long been recognized that laundry compositions function more efficiently in soft water than in water containing significant amounts of dissolved "hardness" cations such as calcium ion, magnesium ion and the like. Heretofore, laundry water has been softened prior to use, usually by passing the water through columns of zeolite or other cation exchange materials. The use of such zeolitic or other cation exchange materials to presoften water requires a separate tank or appliance wherein the water can be percolated slowly through the ion exchange material to remove the undesirable cations. Such pre-softening procedures require an additional expense to the user occasioned by the need to purchase the softener appliance.
Another means whereby fabrics can be optimally laundered under hard water conditions involves the use of water-soluble builder salts and/or chelators to sequester the undesirable hardness cations and to effectively remove them from interaction with the fabrics and detergent materials in the laundering liquor. However, the use of such water-soluble builders necessarily introduces into the water supply certain materials which, in improperly treated sewerage effluents, may be undesirable. Accordingly, a means for providing water-softening builders in detergent compositions without the need for soluble builder additives is desirable.
A variety of methods have been suggested for providing builder and water-softening action concurrently with the deterging cycle of a home laundering operation, but without the need for water-soluble detergent additives. One such method employs a phosphorylated cloth which can be added to the laundry bath to sequester hardness ions and which can be removed after each laundering; see U.S. Pat. No. 3,424,545.
The use of certain clay minerals to adsorb hardness ions from laundering liquors has also been suggested; see, for example, Rao, in Soap Vol. 3 #3 pp. 3-13 (1950); Schwarz, et al. "Surface Active Agents and Detergents", Vol. 2, p. 297 et seq. (1966).
The zeolites, especially the naturally-occurring aluminosilicate zeolites, have been suggested for use in washing compositions; see U.S. Pat. No. 2,213,641; also U.S. Pat. No. 2,264,103.
Various aluminosilicates have been suggested for use as adjuncts to and with detergent compositions; see, for example, U.S. Pat. Nos. 923,850; 1,419,625; and British Pat. Nos. 339,355; 461,103; 462,591; and 522,097.
From the foregoing it is seen that a variety of methods have been heretofore employed to remove hardness cations from aqueous laundering systems concurrently with the deterging cycle of a home laundry operation. However, these methods have not met with general success, primarily due to the inability of the art-disclosed materials to rapidly and efficiently reduce the free polyvalent metal ion content of the aqueous laundering liquor to acceptable hardness levels. To be truly useful in laundry detergent compositions, an ion exchange material must have sufficient cation exchange capacity to significantly decrease the hardness of the laundry bath without requiring excessive amounts of the ion exchanger. Moreover, the ion exchange material must act rapidly, i.e., it must reduce the cation hardness in an aqueous laundry bath to an acceptable level within the limited time (ca. 10-12 minutes) available during the deterging cycle of a home laundering operation. Optimally, effective ion exchange materials should be capable of reducing calcium hardness to about 1 to 2 grains per gallon within the first 1 to 3 minutes of the deterging cycle. Finally, useful cation exchange builders are desirably substantially water-insoluble, inorganic materials which present little or no ecological problems in sewage.
It has now been found that certain aluminosilicate materials have both the high ion exchange capacity and the rapid ion exchange rate needed for cation exchange builder materials in laundry detergent compositions.
Accordingly, it is an object of the present invention to provide detergent compositions containing insoluble, inorganic aluminosilicate ion exchange materials.
It is a further object herein to provide methods for laundering fabrics using the aforesaid detergent compositions.
These and other objects are obtained herein as will be seen from the following disclosure.